The development of microporous foams is the subject of substantial commercial interest. Such foams have found utility in various applications, such as thermal, acoustic, electrical, and mechanical (e.g., for cushioning or packaging) insulators; absorbent materials; filters; membranes; floor mats; toys; carriers for inks, dyes, lubricants, and lotions; and the like. References describing such uses and properties of foams include Oertel, G., “Polyurethane Handbook”; Hanser Publishers: Munich, 1985, and Gibson, L. J.; Ashby, M. F., “Cellular Solids. Structure and Properties”; Pergamon Press: Oxford, 1988. The term “insulator” refers to any material which reduces the transfer of energy from one location to another. The term “absorbent” refers to materials which imbibe and hold or distribute fluids, usually liquids, an example being a sponge. The term “filter” refers to materials which pass a fluid, either gas or liquid, while retaining impurities within the material by size exclusion, interception, electrostatic attraction, adsorption, etc. Other uses for foams are generally obvious to one skilled in the art.
Open-celled foams prepared from High Internal Phase Emulsions (hereinafter referred to as “HIPE”) are particularly useful in a variety of applications including absorbent disposable articles (U.S. Pat. No. 5,331,015 (DesMarais et al.) issued Jul. 19, 1994, U.S. Pat. No. 5,260,345 (DesMarais et al.) issued Nov. 9, 1993, U.S. Pat. No. 5,268,224 (DesMarais et al.) issued Dec. 7, 1993, U.S. Pat. No. 5,632,737 (Stone et al.) issued May 27, 1997, U.S. Pat. No. 5,387,207 (Dyer et al.) issued Feb. 7, 1995, U.S. Pat. No. 5,786,395 (Stone et al.) Jul. 28, 1998, U.S. Pat. No. 5,795,921 (Dyer et al.) issued Aug. 18, 1998), insulation (thermal, acoustic, mechanical) (U.S. Pat. No. 5,770,634 (Dyer et al.) issued Jun. 23, 1998, U.S. Pat. No. 5,753,359 (Dyer et al.) issued May 19, 1998, and U.S. Pat. No. 5,633,291 (Dyer et al.) issued May 27, 1997), filtration (Bhumgara, Z. Filtration & Separation 1995, March, 245-251; Walsh et al. J. Aerosol Sci. 1996, 27, 5629-5630; published PCT application W/O 97/37745, published on Oct. 16, 1997, in the name of Shell Oil Co.), and various other uses. The HIPE process provides facile control over the density, cell and pore size and distribution, proportion of cell struts to windows, and porosity in these foams.
Economics is an important issue in making HIPE foams commercially attractive. Especially, it is important to make HIPE efficiently and with cost effective equipment. There are some attempts to achieve the goal; however there is still a substantial opportunity for substantial improvement of efficiency during the process for making HIPE. Accordingly, it would be desirable to develop a method for reducing material loss during the process for making and curing the HIPE and to use cost effective equipment.